By the end of the decade of 1920 he enters to the Communist Party of Argentina. In 1933 he joined the first Argentine union of plastic artists. That same year he exposed at the National Hall of Beautiful Arts.
Along with Antonio Berni, Spilimbergo and Siqueiros, he made the murals in the villa of Natalio Botana, in Don Torcuato. In 1939 he goes to Paris, city where he attends the atelier of cubist painter André Lothe, and travels across Europe perfecting his art next to Braque, Léger and Picasso, among others. Castagnino returns to Argentina in 1941, where he obtains the title of architect in the University of Buenos Aires.
He received several awards such as the Great Prize of Honor of the Argentine National Hall (1961), the Medal of Honor of the International Fair of Brussels (1958) and the special award of drawing in the II Biennial of Mexico (1962). His illustrations to the national poem Martín Fierro of José Hernández, published by EUDEBA (University of Buenos Aires press), gained wide recognition.